1. Field of the Invention
The field of art to which this invention relates is goniometers. Specifically, this invention relates to micro goniometers for scanning microscopy.
2. Description of the Related Art
With the advent of scanning probe microscopes such as scanning tunneling microscopes (STM) and atomic force microscopes (AFM) several methods have been developed to use their small scale processing capability for high density data storage. In these methods, a probe, or tip interacts with atoms or molecules on a substrate surface to form bumps. The bump forms a bit of information which is represented in a base two (binary) format (i.e., as a 1 or a 0). Movement of the tip is typically controlled by a goniometer. However, goniometers of the prior art limit the movement of the tip to the z-direction, that is, normal to the substrate surface. An example of such a use is disclosed in U.S. Pat. No. 5,327,625 to Clark et al. Although these methods have their advantages, such as high storage density, they are plagued by several disadvantages.
The main disadvantage of scanning probe microscope data storage is that the speed of writing and replication is prohibitively slow. Conventional magnetic and CD-ROM recording rates are approximately 10.sup.8 and 1.510.sup.6 bits/second respectively, while STM atom writing is less than 1 bit/second.
Additionally, writing at the atomic level is usually performed at very cold temperatures and in a vacuum. The equipment used to perform atomic scale writing is therefore very sophisticated and expensive. There are also disadvantages in reading the information written at the atomic level. Atomic scale resolution of the media surface is necessary to read the data. This also requires sophisticated and expensive equipment.
While scanning probe microscopes have advanced the art of microscopy on the atomic scale, their potential has not been fully realized due to the inflexibility of the tip used to interact with the substrate surface.
In addition to high density data storage, scanning probe microscopes, particularly the AFM, have been used in recent years to probe molecular interactions. In this method, the AFM tip of a specific molecular structure is brought close to the substrate surface which is also of a specific molecular structure. The tip is supported on the free end of a cantilever, the deflection of the tip cantilever as a function of tip displacement reveals the force of interaction between the two surfaces (the tip and the substrate) as a function of distance. This force relates to the nature of the interaction. Although the force measurement and the displacement are accurate, the surface area of the interacting surface is not well controlled because the tip angle is fixed and unknown relative to the substrate surface.